Convert a circular tube into an oval tube
Since I don't really know your topology, I better start from scratch. If I interpret your question right, here's how I would approach it:

I assume a Blender unit to be 1 meter. I don't use metrics, so you might have to adapt your values.

Create a cirle. In the redo panel to the left, enter the desired resolution (I chose 64) and as radius, enter .214/2



Go into Edit Mode with TAB, hit A to clear the selection and use B to select half of it (you could do a negative border select with MMBand spare the A).

Then press Y.

It's called split and will duplicate the verts at the border of your selection. In this case it means you now have two half circles. One is selected, one isn't.



With the right half still selected, move the right circle to the right with GX .05 RETURN, right?

Select all with AA and fill it with F



Inset the face with I .004 RETURN



Delete the inner face using X, "Only Faces"



Go into front view, select all and extrude up with E .325 RETURN


The finished tube with, I hope, the right dimensions.